Cytoskeletons are Functionally Differentiated in the Squid Giant Axon

Abstract

The neuron is a highly differentiated cell for receiving, processing, conducting and transmitting signals. Morphologically distinguishable portions, such as the cell body, dendrites and the axon, are functionally differentiated for this task. The squid giant axon has long been used for physiological and biochemical studies of the various functional sites in the neuron because of its exceptional large size. Most studies have concentrated on the axonal transport and impulse conduction. The central part of the giant axon, the central axoplasm, can easily be extruded with a tiny roller without loss of its electrical excitability and large amounts of transported vesicles are observed in the central axoplasm. These facts suggest that (1) the central axoplasm is functionally differentiated from the peripheral axoplasm, the axoplasm remaining in the axon after the extrusion, and (2) the both parts have distinct rheological properties (for review see Matsumoto et al., 1989).